1. Field of the Invention
Embodiments of the present invention relate to semiconductor devices such as power devices and switching ICs for high frequency application, and in particular, to semiconductor devices in power semiconductor elements.
2. Description of the Background
Power devices are used for switching devices in power converter applications. A conventional power device is disclosed in Japanese Unexamined Patent Application Publication No. 2007-194442 (“JP 2007-194442”), for example. FIG. 3 shows a construction of the power device. The power device comprises: a heat sink 101 made of a good thermal conductivity material composed of a base plate 101a and a cooling fin 101b; an insulating substrate 103, mounting a semiconductor chip 102, fixed on the base plate 101a; and a resin casing 104 surrounding the semiconductor chip 102 and the insulating substrate 103. The power device is formed in a form of a monolithic module. Electrical connection is held between the surface electrodes of the semiconductor chips 102 and the circuit pattern 106 on the insulating substrate 103 usually by joining them with aluminum wires 105.
Japanese Unexamined Patent Application Publication No. 2011-142124 (“JP 2011-142124”) proposes a semiconductor device in which a plurality of units of a semiconductor module is accommodated in a bolted unit with elastic adhesive, and the bolted unit is mounted on a cooling body.
In the conventional example disclosed in JP 2007-194442, the power semiconductor devices are used in power conversion devices such as inverters. In order to construct a full bridge circuit, for example, the terminals 108 projecting out upward through the lid 107 for enclosing the top of the resin casing 104 shown in FIG. 3 are connected with wiring means such as a substrate or bus bars to carry out wiring between discrete semiconductor devices. In addition, external connection to an output side and an input side, or power supply side, are also necessarily conducted.
A required external configuration of the semiconductor device is determined by constraints of these conditions and the overall external configuration of the device. Corresponding to the application field of the semiconductor device, the number of the insulating substrates 103 in the internal structure of the semiconductor device and the connection between the insulating substrates are determined according to the configuration.
To meet increased demand for power conversion devices in recent years, and to take advantage of improved performance of semiconductor chips, each class of semiconductor devices corresponding to the demands for specific ratings are assembled plentifully. This assembly needs preparation for each of the semiconductor chips 102, insulating substrates 103, resin casings 104, lids 107 and terminals 108, corresponding to each necessary capacity.
On this background, there are numerous types of the external configuration of the insulating substrate 103 and the interconnection between the insulating substrates 103 on the heat sink 101. This increases the number of types of required tools necessary for production. Moreover, the demanded types of semiconductor devices are changing rapidly, which shortens the effectively employed period of production equipment and tools.
These situations hinder cost reduction and, in addition, lower efficiency in mass-production due to instability of quality. It is becoming difficult to provide the semiconductor devices in inexpensive prices.